(a) Field of the Invention
The present invention relates to a control system of a starting motor for an automatic transmission vehicle. More particularly, the present invention relates to a control system of a starting motor for an automatic transmission vehicle that prevents a malfunction of the starting motor.
(b) Description of the Related Art
An engine of an automatic transmission vehicle can be started only when a shift lever position is parking (P) or neutral (N). Such function is controlled by an inhibitor switch. If the D, 2, L, or R node is selected in the inhibitor switch, the engine is not started.
However, the inhibitor switch may not determine an exact position of the shift lever because of a complex structure of the inhibitor switch and wearing of the nodes of the inhibitor switch.
To solve such problems, a control system of a starting motor using a position sensor has been designed.
In such a system, a position sensor detects a shift lever position and generates a signal corresponding thereto. A shift control module receives the signal and determines whether the shift lever position is the parking (P) or neutral (N) position. The shift control module controls the starting relay so as to operate the starting motor.
However, when the vehicle is exposed to very low temperatures, battery voltage drops rapidly in a few milliseconds. Accordingly, the processor does not operate normally because of the low battery voltage. Therefore, the processor does not control the starting relay. The engine thus may not start in very low temperatures.
To solve such problems, the shift control module further includes a buffer so that the engine can be started in very low temperatures when the processor does not operate normally. The buffer amplifies the starting control signal transmitted from the processor and outputs the starting control signal to a first switching element.
However, since the buffer is used to start the engine in very low temperatures, many problems may occur. Since the starting control signal of the processor is amplified by the buffer during a predetermined time ΔT1, the starting control signal applied to the starting relay is delayed.
Therefore, if the shift lever position is changed to a drive (D) position or a reverse (R) position during the delay time, the starting relay is turned on regardless of the shift lever position. Thus, problems such as a quick start may occur. Such problems may occur under normal conditions as well as in very low temperatures.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.